package org.jboss.windup.reporting.freemarker;

import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.logging.Logger;

import org.jboss.forge.furnace.Furnace;
import org.jboss.windup.config.GraphRewrite;
import org.jboss.windup.config.Variables;
import org.jboss.windup.config.operation.GraphOperation;
import org.jboss.windup.reporting.service.ReportService;
import org.jboss.windup.util.exception.WindupException;
import org.ocpsoft.rewrite.context.EvaluationContext;

import freemarker.template.Template;
import freemarker.template.TemplateException;

/**
 * This class is used to produce a freemarker report (and the associated ReportModel) from outside of an Iteration context.
 *
 * @author <a href="mailto:jesse.sightler@gmail.com">Jesse Sightler</a> <jesse.sightler@gmail.com)
 */
public class FreeMarkerOperation extends GraphOperation {
    private static final Logger LOG = Logger.getLogger(FreeMarkerOperation.class.getName());

    private final Furnace furnace;
    private final String templatePath;
    private final String outputFilename;
    private List<String> variableNames = new ArrayList<>();

    protected FreeMarkerOperation(Furnace furnace, String templatePath, String outputFilename, String... varNames) {
        this.furnace = furnace;
        this.templatePath = templatePath.replace('\\', '/');
        this.outputFilename = outputFilename;
        this.variableNames = Arrays.asList(varNames);
    }

    /**
     * Create a FreeMarkerOperation with the provided furnace instance template path, and varNames.
     * <p>
     * The variables in varNames will be provided to the template, and a new ReportModel will be created with these variables attached.
     */
    public static FreeMarkerOperation create(Furnace furnace, String templatePath, String outputFilename,
                                             String... varNames) {
        return new FreeMarkerOperation(furnace, templatePath, outputFilename, varNames);
    }

    @Override
    public void perform(GraphRewrite event, EvaluationContext context) {
        try {
            ReportService reportService = new ReportService(event.getGraphContext());
            Path outputDir = reportService.getReportDirectory();
            Path outputPath = outputDir.resolve(outputFilename);

            LOG.info("Reporting: Writing template \"" + templatePath + "\" to output file \""
                    + outputPath.toAbsolutePath().toString() + "\"");

            freemarker.template.Configuration freemarkerConfig = FreeMarkerUtil.getDefaultFreemarkerConfiguration();
            Template template = freemarkerConfig.getTemplate(templatePath);

            Variables varStack = Variables.instance(event);

            // just the variables
            Map<String, Object> vars = FreeMarkerUtil.findFreeMarkerContextVariables(varStack,
                    variableNames.toArray(new String[variableNames.size()]));

            vars.put("event", event);

            // also, extension functions
            Map<String, Object> freeMarkerExtensions = FreeMarkerUtil.findFreeMarkerExtensions(furnace, event);

            Map<String, Object> objects = new HashMap<>(vars);
            objects.putAll(freeMarkerExtensions);

            try (FileWriter fw = new FileWriter(outputPath.toFile())) {
                template.process(objects, fw);
            }
        } catch (IOException e) {
            throw new WindupException("Failed to write template results due to: " + e.getMessage(), e);
        } catch (TemplateException e) {
            throw new WindupException("FreeMarkerOperation TemplateException: " + e.getMessage(), e);
        }
    }

    @Override
    public String toString() {
        return "FreeMarkerOperation[template=" + templatePath + ", output=" + outputFilename + "]";
    }
}
